If earth rotates on its own axis slowly (say half speed ) what would happen?
i think the possible changes would be


A day will be of 48 hours life on earth willl be disturbed
atmosphere will be vanished in polar regions ( lack of oxygen to breathe)
water in oceans will gradually move towards poles.
continents will appear in on equator and vanish from the poles ( may be an equatorial continents with only 2 oceans .)
due to lesser spin of earth the iron core inside earth will produce less magnetic field and more solar radiation will blast through the magnetosphere causing solar radiations and ultimately we all can die.

please add some more points in this disscussion